Method and system for determining shape in plane to be determined in atmosphere of scattering materials

ABSTRACT

The invention relates to a method for determining the shape in a plane to be determined in atmosphere of scattering materials. The method includes comprising the steps of irradiating light on a first line to be determined being imagined on the plane to be determined in the atmosphere of scattering materials to extract a first picture signal at the time of picking up the first line to be determined; at the same time, irradiating light on a second line to be determined being imagined at a position with a prescribed distance apart from the first line to be determined to extract a second picture signal at the time of picking up the second line to be determined; then, subtracting the second picture signal from the first picture signal to extract a fresh picture signal; and operating two-dimensional position coordinates of a first image of line to be determined on the picture in which the first line to be determined has been picked up on the basis of the fresh picture signal to extract three-dimensional position coordinates of the first line to be determined in the plane to be determined through coordinate conversion of the two-dimensional position coordinates. Further, the invention relates to a system in which the scattering materials are cleared away by jetting gas into the atmosphere of scatttering materials prior to picking up of the lines to be determined.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and system for determining theshape in a plane to be determined in atmosphere of scattering materials.More particularly the present invention relates to a method fordetermining the shape in a plane to be determined to which light-sectionmethod is applied in such atmosphere where scattering materials such asdust, mist and the like float as in the case of the interior of the topof a blast furnace.

2. Description of the Prior Art

Heretofore, light-section method has been known as a method fordetermining a position, shape, dimension, displacement and the like ofan object to be determined. In the case of determining the shape in aplane to be determined by utilizing such light-section method, theoperation is carried out, as illustrated in FIG. 1, in accordance withsuch manner that a projector 2 and a pick up means 4 are employed, lightis irradiated on a line 8 to be determined being imagined on a plane 6to be determined by means of the projector 2, the line 8 to bedetermined is picked up by means of the pickup means 4, and the shape inthe plane to be determined is obtained on the basis of the picturepicked up. More specifically, first, either a certain plane (light cutsection) a b c is scanned by means of light beam emitted from a point ain the projector 2 at a prescribed rate, or belt-like light rays areirradiated onto such certain plane to illuminate the line 8 to bedetermined, and the line 8 is picked up by utilizing the pickup means 4placed outside the certain plane a b c. The line 8 to be determined ispicked up as an image of light locus in the case where scanning iseffected with light beam, whilst the line 8 is picked up as a luminanceline image along the line to be determined in the case where belt-likelight rays are irradiated. Then, two-dimensional position coordinates ofthe respective points of an image of line to be determined on thepicture picked up are extracted, and further three-dimensional positioncoordinates in the respective points of the line to be determined on theplane to be determined are extracted from the resulting two-dimensionalposition coordinates and a geometrical arrangement defined by thecertain plane a b c and the pickup means by means of coordinateconversion. Furthermore a plurality of lines to be determined areimagined on the plane 6 to be determined, light is irradiated on therespective lines to be determined by varying an azimuth of the certainplane a b c, and three-dimensional position coordinates in therespective points of the respective lines to be determined in accordancewith a similar manner to that mentioned above. Then, when envelopingsurface is extracted from these three-dimensional position coordinates,the shape in the plane to be determined can be obtained.

However, since such light-section method utilizes light, ifenvironmental condition of such determination is in atmosphere ofscattering materials, there arises such disadvantage that a part of thelight projected on the plane to be determined is scattered by floatingscattering materials, and when the line to be determined is picked up inthis condition, a background picture (image of scattered light) ispicked up other than the image of line to be determined. Thus, therearise such problems in that such background picture changes itsdistribution of luminance in response to the change in a distribution ofspatial and time concentration of scattering materials, and generationof such background picture results in deterioration in SN ratio of theimage of line to be determined, very difficult detection, or such a casewhere the background picture is erroneously detected as the image ofline to be determined. When these phenomena are described in conjunctionwith a blast furnace, there cause such problems that laser beam does notreach the plane to be determined, and that picking up of luminous spotsor luminous lines on the plane to be determined becomes difficult in thecase where a dust density is very high either immediately after charginga raw material into the blase furnace in which a Bell type chargingmeans is utilized, or during charging of the raw material into the blastfurnace in which a Bell-less type charging means is employed.

Moreover, in the case when a profile in the stock surface of charge inthe top of a blast furnace is determined, emission from the core of thefurnace frequently occurs, such emission is picked up as a passiveimage, such passive image functions similarly to the case of theabove-mentioned background picture so that there arise similar problemsto those as mentioned above.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above describedproblems. Accordingly, an object of the present invention is to providea method for determining the shape in a plane to be determined inatmosphere of scattering materials by which the shape in the plane to bedetermined can favorably be determined even in an unfavourableenvironmental condition in which background picture and emission exist.

Furthermore, another object of the present invention is to provide asystem for determining the shape in a plane to be determined inatmosphere of scattering materials by which the shape in the plane to bedetermined can be determined even in the atmosphere of scatteringmaterials such as dust, mist and the like without being unfavorablyaffected by such scattering materials.

The above described objects are attained by the present inventionrelating to a method for determining the shape in a plane to bedetermined in atmosphere of scattering materials comprising the steps ofirradiating light on a first line to be determined being imagined on theaforesaid plane to be determined in the atmosphere of scatteringmaterials to extract a first picture signal at the time of picking upthe aforesaid first line to be determined; at the same time, irradiatinglight on a second line to be determined being imagined at a positionwith a prescribed distance apart from the aforesaid first line to bedetermined to extract a second picture signal at the time of picking upthe aforesaid second line to be determined; then, subtracting theaforesaid second picture signal from the aforesaid first picture signalto extract a fresh picture signal; and operating two-dimensionalposition coordinates of a first image of line to be determined on thepicture in which the aforesaid first line to be determined has beenpicked up on the basis of the aforesaid fresh picture signal to extractthree-dimensional position coordinates of the aforesaid first line to bedetermined in the aforesaid plane to be determined through coordinateconversion of the aforesaid two-dimensional position coordinates.

Moreover, the above-mentioned objects are attained by the presentinvention relating to a method for determining the shape in a plane tobe determined in atmosphere of scattering materials comprising the stepsof extracting a first picture signal at the time when a first line to bedetermined being imagined on the aforesaid plane to be determined in theatmosphere of scattering materials is picked up by scanning theaforesaid first line to be determined with light beam having aprescribed rate; at the same time, extracting a second picture signal atthe time when a second line to be determined being imagined at aposition with a prescribed distance apart from the aforesaid first lineto be determined is picked up by scanning said second line to bedetermined with light beam having a higher scanning rate than theaforesaid prescribed scanning rate; then, subtracting the aforesaidsecond picture signal from the aforesaid first picture signal to extracta fresh picture signal; and operating two-dimensional positioncoordinates of a first image of line to be determined on the picture inwhich the aforesaid line to be determined has been picked up on thebasis of the aforesaid fresh picture signal to extract three-dimensionalposition coordinates of the aforesaid first line to be determined in theaforesaid plane to be determined through coordinate conversion of theaforesaid two-dimensional position coordinates. In this case, it ispreferable that the aforesaid prescribed scanning rate of light beamwith which the aforesaid first line to be determined is scanned has amagnitude satisfying such a condition that a rate of a luminous spotimage on a picture corresponding to luminous spots on the aforesaidfirst line to be determined is equal to or less than a ratio of adiameter of the aforesaid luminous spot image on the picture to a periodof scanning the picture; and the aforesaid scanning rate of light beamwith which the aforesaid second line to be determined is scanned has amagnitude satisfying such a condition that a time for passing theaforesaid luminous spot image through the surface of the aforesaidpicture is equal to or shorter than the aforesaid period of scanning thepicture.

In addition, the above stated objects are attained by the presentinvention relating to a system for determining the shape in a plane tobe determined in atmosphere of scattering materials comprising aprojector for projecting light upon a line to be determined beingimagined on a plane to be determined in atmosphere of scatteringmaterials; a gas jetting means for jetting gas of a higher pressure thanthat of the aforesaid atmosphere of scattering materials thereinto; apickup means for picking up the aforesaid line to be determined afterjetting the aforesaid gas by means of the aforesaid gas jetting means,thereby to output a picture signal; a position coordinate detectioncircuit for extracting two-dimensional position coordinates of a line tobe determined on a picture from the aforesaid picture signal outputtedfrom the aforesaid pickup means; and an arithmetic unit for operatingthree-dimensional position coordinates of the aforesaid line to bedetermined on the aforesaid plane to be determined by subjecting theaforesaid two-dimensional position coordinates extracted by means of theaforesaid position coordinate detection circuit to coordinateconversion. In accordance with the construction as mentioned above,dust-free gas is jetted from the gas jetting means to clear away thescattering materials on light path in the case where a line to bedetermined is picked up by means of the pickup means and as a result, aplane to be determined can be picked up without being unfavorablyaffected by the scattering materials.

Therefore, according to the present invention, such an excellentadvantage that a shape of the plane to be determined can favorably bedetermined even in atmosphere of scattering materials.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned features and objects of the present invention willbecome more apparent by reference to the following description taken inconjunction with the accompanying drawings, wherein like referencednumerals denote like elements, and in which:

FIG. 1 is an explanatory view for explaining a conventionallight-section method;

FIG. 2 is an explanatory view for explaining the principles of thepresent invention;

FIGS. 3 through 5, inclusive, are diagrams illustrating picture A,picture B and picture C in the principle of the present invention,respectively;

FIG. 6 is a block diagram illustrating a circuit for extracting pictureC from picture A and picture B in the aforesaid present invention;

FIG. 7 is a block diagram illustrating an embodiment in the case whenthe present invention is applied to a determination of the surface ofcharge in a furnace;

FIGS. 8 and 9 are front and elevational views each showing anarrangement of a beam scanner and a television camera in FIG. 7;

FIGS. 10 and 11 are diagrams illustrating picture A and picture B in theaforesaid embodiment of the present invention, respectively;

FIGS. 12(a), (b) and (c) are diagrams illustrating video signal A ofpicture A in FIG. 10, video signal B of picture B in FIG. 11, and avideo signal obtained by subtracting video signal B from video signal A,respectively;

FIG. 13 is a diagram showing lines to be determined being imagined inthe case when the whole surface of charge in a furnace is determined inthe embodiment of the present invention;

FIGS. 14 through 17, inclusive, are diagrams each illustrating a picturein the principle of the present invention;

FIG. 18 is a block diagram showing a circuit for extracting picture Cfrom pictures A and B in the aforesaid principle of the presentinvention;

FIG. 19 is a diagram for explaining a relationship between a diameter ofa laser luminous spot image and a rate of the laser beam passing througha picture;

FIG. 20 is a diagram illustrating a relationship between a picturescanning period T and an electric potential;

FIG. 21 is a diagram illustrating changes in electric potential of anarbitrary point A in case of R/v<T;

FIG. 22 is a block diagram illustrating an embodiment of the presentinvention; and

FIG. 23 is a block diagram illustrating another embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principle of the present invention will be described hereinbelow byreferring to FIGS. 2 through 6, inclusive. In the following description,it is to be understood that an explanation will be made upon such anexample where a background picture due to scattering materials has beenremoved. As shown in FIG. 2, a projector 2 and an image pickup means 4are arranged in accordance with a similar manner to that in aconventional light-section method. Then, either a certain plane a b c isscanned by means of light beam emitted from a point a in the projector2, or belt-like light rays are irradiated onto such certain plane toilluminate a first line 10 to be determined being imagined on a plane 6to be determined. Thereafter, the line 10 to be determined is picked upby the use of the image pickup means 4. A picture A obtained by suchpickup of image signal is illustrated in FIG. 3. In this picture A, afirst image 10' of line to be determined and a background picture 14'due to atmosphere of scattering materials 14 are picked up. And apicture signal corresponding to the picture A is signal-processed bymeans of a signal processing circuit 16 illustrated in FIG. 6 and whicheffects removal of high frequency wave, differential processing, andgain adjustment, and then the resulting signal is stored in a memoryarithmetic circuit 18.

Succeedingly, the projector 2 is rotated with a prescribed angle in ahorizontal plane to change a projecting light cut plane from the plane ab c to the one a b' c' as shown in FIG. 2, and light is irradiated on asecond line 12 to be determined being imagined at a position with aprescribed distance l apart from the first line 10 to be determined inaccordance with a similar manner to that mentioned above, whereby thesecond line 12 to be determined is picked up by means of the imagepickup means 4. A picture B obtained by such pickup of image signal isillustrated in FIG. 4. In this picture B, a second image 12' of line tobe determined and a background picture 14" due to atmosphere ofscattering materials 14 are picked up. Then, a picture signalcorresponding to the picture B is signal-processed by means of a signalprocessing circuit 20 for effecting removal of high frequency wave,differential processing, and gain adjustment similarly to those in thesignal processing circuit 16 as illustrated in FIG. 6, and then theresulting signal is inputted into the memory arithmetic circuit 18. Inthe memory arithmetic circuit 18, the picture signal inputted from thesignal processing circuit 20 is subtracted from the picture signalcorresponding to the picture A which has already been stored, thereby toobtain a fresh picture signal. A picture C corresponding to this freshpicture signal is illustrated in FIG. 5. As is understood from thedrawing, the background image has already been removed in FIG. 5 bymeans of the subtraction in the memory arithmetic circuit 18, thus onlythe first image 10' of line to be determined appears in FIG. 5.Moreover, it is to be noted that the second image 12' of line to bedetermined becomes a negative value by means of the subtraction so thatthe same does not appear in the picture C.

In addition, it is suitable that the distance l between the first andsecond lines to be determined is several times longer than a width ofluminance line (a diameter of luminous spot in case of scanning by meansof light beam). Further it is advantageous to improve SN ratio thatwriting operation in the case where a picture signal is stored in amemory arithmetic unit is repeated a number of times upon a series ofvideo pictures obtained by scanning with light beam.

Next, an embodiment in which the present invention is applied to aprofile determination of a charge at the top of a blast furnace will bedescribed by referring to the accompanying drawings.As shown in FIGS. 7,a system of the present embodiment comprises a laser light source 22, areflector 24 for reflecting laser beam from the laser light source 22 atan angle of 90°, a beam scanner 26 for scanning laser beam on a surface30 of the charge at the furnace top, and a television camera 28 as itsimage pickup means. The first signal processing circuit 16 as well asthe second signal processing circuit 20 connected in parallel to thefirst signal processing circuit 16 are connected with the televisioncamera 28. The respective signal processing circuits 16 and 20 areconnected to a scan converter 32 as its memory arithmetic circuit. Thescan converter 32 is connected to a microcomputer 36 through a signalposition detecting circuit 34. Furthermore it is arranged in such thatan azimuth θ of the bean scanner 26 is inputted to the microcomputer 36.

As the scan converter 32, Scan Converter System Model 639 S (Trade name,manufactured by Hughes Co. in U.S.A.) was employed. This scan converterutilizes storage tubes, and a picture is stored in a storage target ascharge pattern. Accordingly, addition and subtraction of the picture canbe effected by controlling discharge and charge with respect to therespective points on the storage target.

Further the beam scanner 26 is composed of a reflector of substantiallyoctangular prism having eight surfaces of reflection and is arranged insuch a way that the angle of each surface of reflection changes byrotating the reflector around the axis thereof as its center.Accordingly, laser beam can be made to scan along the line to bedetermined on the surface 30 of the charge at the furnace top, when thebeam scanner 26 is rotated. Moreover a rotational frequency controller33 for controlling a rotational frequency of a beam scanner 32 isconnected to the shaft of the beam scanner 32.

It is to be noted that the television camera 28 is utilized in suchmanner that the camera is rotated at an angle of 90° with respect to ausual arrangement of a television camera so that video scanning linesappear along the vertical direction of a picture.

The beam scanner 26 and the television camera 28 are placed in the samehorizontal plane at the positions where they are apart at an angle of90° from each other as shown in FIGS. 8 and 9. In addition, the beamscanner 26 and the television camera 28 are positioned with a height ofabout 3000 mm from the highest position of the surface 30 of the chargeat the furnace top.

In the following, operation of the present embodiment will be describedby referring to the accompanying drawings.

First, laser beam is irradiated from the laser light source 22 andreflected by means of the reflector 24 at an angle of 90° to irradiatethe laser beam reflected upon a surface of reflection of the beamscanner 26. In this case, if a horizontal azimuth of the beam scanner 26is present at θ and rotated with a prescribed rate, scanning is effectedby means of the laser beam along the first line 10 to be determinedbeing imagined on the surface 30 of charge at the furnace top. In thiscondition, the first line 10 to be determined is picked up by the use ofthe television camera 28 at the time when the first line 10 to bedetermined is subjected to at least one scanning. The picture A obtainedby such pickup of image signal is illustrated in FIG. 10 in which thefirst image 10' of line to be determined, the background picture 14' dueto scattering materials 14, and a high temperature luminous part image11 derived from a core part of the furnace are pickedup, respectively,and further reference character L designates video scanning lines, andL.sub.ν a video scanning line at a specified position.

In this situation, a picture signal of the picture A outputted from thetelevision camera 28 is processed by means of the signal processingcircuit 16, and then when the video signal A being expressed by means ofvoltage V and time t on the video scanning line L.sub.ν is extracted,the result is as illustrated in FIG. 12(a). In FIGS. 12(a), (b) and (c),reference character γ corresponds to synchronizing signal, δ scatteringimage, ω₁ laser locus image, and ξ high temperature luminous part image,respectively.

Next, the horizontal azimuth of the beam scanner 26 is set to a value ofθ-η, and scanning is carried out with laser beam along the second line12 to be determined being imaged at the position with a prescribeddistance apart from the first line 10 to be determined. In this case,the magnitude of an angle η is dependent upon the diameter of a luminousspot image on the picture due to laser beam, and the most suitable isusually around 5°. And when the second line 12 to be determined ispicked up by the use of the television camera 28, the picture Billustrated in FIG. 11 is obtained. In FIG. 11, reference numerals 12'and 14" designate the second image of line to be determined, and thebackground picture due to scattering materials, respectively.Furthermore when the video signal B on the video scanning line L.sub.νis extracted by the similar manner to that mentioned above, the resultis as illustrated in FIG. 12(b) in which reference character ω₂designates laser locus image.

In this condition, when the video signal B is subtracted from the videosignal A, a video signal illustrated in FIG. 12 (c) is obtained so thatif the laser locus image ω₁, for example, a mean value thereof isextracted, two-dimensional position coordinates (H, V) on the videosignal L.sub.ν can be obtained in the following signal positiondetecting circuit 34.

Meanwhile, if the above-mentioned processing is applied to all the videoscanning lines L, two-dimensional position coordinates in the respectivepoints of the first image of line to be determined on the picture A areobtained.

Moreover the subtraction of the video signal B from the above describedvideo signal A is effected by controlling charge of the scan converter32. On the other hand, there arises also such a case where the videosignals A and B involve high frequency noises having different positionson the time t-axis, and signal strength of the laser locus images ω₁ andω₂ is considerably smaller than that of the background. Accordingly, inthe present embodiment, the signal processing circuits 16 and 20pretreating separately the video signals A and B are provided as ameasure to counter lowering of SN ratio of signal strength in the laserlocus images so that differential effect and gain adjustment of thesecond signal processing circuit 20 are fixed at a small value ascompared with those of the first signal processing circuit 16.

The two-dimensional position coordinates (H, V) obtained as describedabove are converted into three-dimensional position coordinates (X, Y,Z) of the respective points on the first line 10 to be determined on thesurface 30 of charge at the furnace top by means of the microcomputer 36in accordance with coordinate conversion by adopting horizontal azimuthθ of the beam scanner 26, azimuth of the television camera 28, andgeometrical constants relating to mounting positions of the beam scanner26 and the television camera 28.

Next, as illustrated in FIG. 13, for instance, nine first lines P₁ -P₉to be determined at intervals of 10° are imagined on the surface 30 ofthe charge in furnace, at the same time, second lines q₁ -q₂ to bedetermined being positioned at 5° apart from the first lines P₁ -P₉,respectively, are imagined, and when three-dimensional positioncoordinates at the respective points of the first line P₁ -P₉ to bedetermined on the surface 30 of the charge in furnace are extracted andenveloping surface is extracted from the three-dimensional positioncoordinates are extracted, a shape of the surface 30 of charge infurnace can be obtained in accordance with the manner as describedabove.

In this connection, a ratio of picture data which could not have beendetected or has erroneously been detected with repect to all the picturedata was about 60% in a conventional light-section method, whilst it wasimproved in the ratio of about 40% in the present embodiment.

Then, the principle of the present invention will be describedhereinbelow by referring to FIG. 2 and FIGS. 14 through 18, inclusive.In the following description, it is to be noted that an explanation willbe made upon such an example where a background picture due toscattering materials has already been removed. As shown in FIG. 2, theprojector 2 and the image pickup means 4 are arranged in accordance witha similar manner to that in a conventional light cut method. Thereafter,the certain plane a b c is scanned at a prescribed scanning rate bymeans of light beam emitted from the point a in the project 2 toilluminate the first line 10 to be determined being imagined on theplane 6 to be determined. As a result, continuous luminous spots appearon the first line 10 to be determined, and a series of pictures formedduring a period in which a luminous spot passes through field of view ofthe image pickup means 4 are picked up by utilizing the pickup means 4having a picture scanning period of T second so that a series ofpictures A₁, A₂,-A_(n) illustrated in FIGS. 14(a₁) through 14(a_(n)),inclusive, are obtained. In the respective pictures, light beamluuminous spot images 10₁ ',-10_(n) ' as well as background pictures 14₁',-14_(n) ' due to scattering materials 14 are picked up.

In the above case, since luminance of the light beam luminous spot onthe plane to be determined is generally small, it is preferable topresent a scanning rate of the light beam by which the first line 10 tobe determined is scanned in such that it makes a quantity of theincident light struck upon the image pickup means maximum. In this case,if it is assumed that a rate of travel of the light beam luminous spotimage on a picture is v mm/sec., a picture scanning period of the pickupmeans 4 is T sec., a diameter of the light beam luminous spot image onthe picture is R mm, and resolution of the picture is made to besufficiently smaller than the diameter R of the luminous spot image, atime required for which the light beam luminous spot image 13 passesthrough an arbitrary point A on the picture 11 illustrated in FIG. 19becomes R/v sec. Further the pickup means 4 is the one for storing andkeeping the light struck upon an arbitrary point on the picture aselectric potential (or charge) the maximum T sec. Potential charge inthe case where light of a constant intensity continues at striking uponthe aforesaid arbitrary point is as illustrated in FIG. 20. Therefore,if scanning is effected by means of light beam so as to satisfy thefollowing equation (1) as illustrated in FIG. 21, it can be picked upwith the maximum quantity of incident light:

    vT≦R                                                (1).

A series of the pictures A₁, A₂,-A_(n) are signal-processed by means ofa first signal processing circuit 16 for effecting removal of highfrequency wave, differential processing, and gain adjustment as shown inFIG. 18, and then the resulting pictures are stored in a picture storingmeans 18 in a overlapped manner. The picture A obtained by means of thepicture storing means 18 is shown in FIG. 15. In the picture A, thefirst image 10' of line to be determined and the background picture 14'are picked up.

Then, the projector 2 is rotated with a prescribed angle in thehorizontal plane to change a light cut plane for projecting light beamfrom the plane a b c to the one a b' c', and the second line 12 to bedetermined being imagined at a position with a prescribed distance lapart from the first line to be determined is scanned by means of lightbeam, a series of pictures B₁, B₂,-B_(n) are picked up by the use of thepickup means 4 having a similar picture scanning period of T sec. tothat mentioned above, the so picked up pictures are signal-processed bymeans of the second signal processing circuit 20, and then therespective pictures B₁, B₂ ,-B_(n) are substracted from the picture Astored in the picture storing means 18. In this case, the picture Bobtained by overlapping a series of the pictures B₁, B₂,-B_(n) with eachother is as illustrated in FIG. 16 in which the second image 12' of lineto be determined and the background picture 14" are picked up,respectively. Moreover the picture C obtained by subtracting a series ofthe pictures B₁, B₂,-B_(n) from the picture A (as a naturealconsequence, the picture obtained by subtracting the picture B from thepicture A) becomes the one as illustrated in FIG. 17 in which thebackground picture is removed, and a good quality of the picture havinga high SN ratio is obtained.

It is suitable that the prescribed distance l between the aforesaidfirst and second lines 10 and 12 to be determined is arranged, asmentioned above, in such a way that the distance between the first andsecond images 10' and 12' of lines to be determined is several timeslonger than a width of each image.

On one hand, an object of the picture B in which the second line 12 tobe determined has been picked up is not to pick up the second image ofline to be determined, but to remove the background picture 14' of thepicture A and a passive spot image, and accordingly it is sufficient forattaining such object that the whole image has been picked up in onepicture. Therefore, it is arranged in such that picking-up of imagesignal is effected by means of scanning so as to become a transit time tof the liminous spot image passing through the picture on the surfacethereof equal to or shorter than a picture scanning period T, and theresulting picture is amplified n times, that is, subtraction is effectedafter making level of the resulting picture to be the same level of thebackground picture and the passive spot image in the picture A, so thatthe scanning period can be shortened.

Two-dimensional position coordinates of the first image of line to bedetermined on the picture C obtained as described above are extractedand when the result is subjected to coordinate conversion,three-dimensional position coordinates of the first line to bedetermined can be obtained.

Next, in the case when the present invention is applied to determinationof a profile of the charge at furnace top, the above-mentioned systemshown in FIGS. 7-9 is utilized.

In the following, operation of an embodiment of the present inventionwill be described hereinbelow by referring to the accompanying drawings.

First, laser beam is irradiated from the laser light source 22 and thelaser beam is reflected at an angle 90° by means of the reflector 24 toirradiate the reflected laser beam onto a surface of reflection of thebeam scanner 26. In this case, a horizontal azimuth of the beam scanner26 is preset at θ and at the same time, a rotational frequency of thebeam scanner 26 is controlled by means of a rotational frequencycontroller 33, whereby scanning is effected by means of laser beam alongthe first line 10 to be determined at such a rate of scanning in which aquantity of incident light becomes maximum, and in this situation thefirst line 10 to be determined is picked up by the use of the televisioncamera 28. In the present embodiment, the scanning was carried out insuch a way that a time required for transferring a luminous spot imagefrom one end to the other end of a picture came to be about 6 seconds,and such image signal was picked up by utilizing a television camerahaving a picture scanning time T of 1/30 second. Thus, a number ofpictures picked up during a period where one scanning of the first line10 to be determined was effected was about 200 sheets. A series ofpictures consisting of such number of pictures of about 200 sheets wereprocessed by means of the first signal processing means 16, then thepictures thus processed were stored in the scan converter 24 inoverlapped manner, and as a result, a similar picture to that of FIG. 15was obtained.

Next, the horizontal azimuth of the beam scanner 26 is set to a value ofθ-α, and scanning is carried out with laser beam along the second line12 to be determined being imagined at the position with a prescribeddistance apart from the first line 10 to be determined. In this case,the magnitude of an angle α is dependent upon the diameter of a luminousspot image on the picture due to laser beam, but the most suitable isusually around 5°, and a scanning rate of the second line 12 to bedetermined is made to be larger than that of the first line 10 to bedetermined.

Then, the second line 12 to be determined is picked up by the use of thetelevision camera 28, the image signal picked up is signal-processed byemploying the signal processing circuit 20 having a prescribed gainconstant, and thereafter a picture of the output from the second signalprocessing circuit 20 is subtracted from the picture stored in the scanconverter 32. The resulting picture is similar to that illustrated inFIG. 17 in which the background picture and the luminous part image areremoved, and two-dimensional position coordinates (H, V) in therespective points of the first image of line to be determined can beobtained from such picture.

The two-dimensional position coordinates (H, V) obtained as mentionedabove are similarly processed in accordance with the manner as describedabove by means of the microcomputer 36 so that a shape of the surface 30of charge in furnace is obtained.

In this connection, a ratio of picture data which could not have beendetected or has erroneously been detected with respect to all thepicture data was about 60% in a conventional light cut method, whilst itwas improved in the ratio of about 20% in the present embodiment.

Further it is to be noted that the explanation has been made upon suchan example in which a picture signal is subtracted by the use of thescan converter in the above description, but such subtraction treatmentmay be carried out as mentioned hereinbelow by utilizing digitalmemories and a microcomputer. Namely, the treatment is carried out insuch a way that picture signals pretreated are separately stored in therespective digital memories, and data of address corresponding to thesame video scanning lines are read from both the digital memories,thereby to effect the subtraction. A specific example of the digitalmemories includes Video Frame Memory VMF-1 (Trade name, manufactured byToko K.K.).

In the following, embodiments of the present invention will be describedin detail by referring to the accompanying drawings. An embodiment ofthe system according to the present invention is shown in FIG. 22 iswhich the system comprises a projector 40 for projecting laser beam uponline 8 to be determined being imagined on a surface 30 of charge as asurface to be determined in atmosphere of scattering materials; atelevision camera 28 as a pickup means in which line 8 to be determinedis picked up, and the picture signal is outputted therefrom; and a gasjetting means 42 for jetting gas having a higher pressure than thepressure of the atmosphere of scattering materials into the atmosphere.The projector 40 is composed of a laser light source 22, a reflector 34,and a beam scanner 26 disposed on the outside of a projection window 43aprovided in a furnace wall. In this construction, laser beam emittedfrom the laser light source 22 is reflected by the reflector 24 in adirection of the surface of reflection of the beam scanner 26, andscanning with the laser beam is effected along the line 8 to bedetermined by means of the beam scanner 8.

The television camera 28 is placed on the outside of a projection window43b provided on the furnace wall in the top portion of the furnace topin such that the line 8 to be determined comes within the range of thetelevision camera. A signal processing circuit 44 for effecting removalof high frequency, differential processing, and gain adjustment withrespect to the picture signal outputted from the television camera 28 isconnected with the television camera 28, and further a positioncoordinate detection circuit 34 for detecting two-dimensional positioncoordinates (H, V) of an image of line to be determined on the picturepicked up is connected with the signal processing circuit 44. Moreover amicrocomputer as an arithmetic unit for operating three-dimensionalposition coordinates (X, Y, Z) of the line 8 to be determined on thesurface 30 of charge in a furnace from the two-dimensional coordinates(H, V) being the output of the position coordinate detection circuit 34by means of coordinate conversion is connected with th positioncoordinate detection circuit 34. Besides an indicator 48 for displayingthe three-dimensional position coordinates (X, Y, Z) is connected to themicrocomputer 36.

The gas jetting means 42 consists of a gas holder 42a for storingdust-free blast furnace exhaust gas, solenoid valve 42b connected to thegas holder 42a through a gas passage, and a nozzle 42 provided on theextreme end of the solenoid valve 42b. And the solenoid valve 42b isswitched and controlled by means of a control circuit 46 for controllingwake-up of the microcomputer 36.

Furthermore an angle detecting means 50 for detecting a horizontalazimuth θ of a shaft of the beam scanner 26 is connected with the beamscanner 26 in such manner that output of the angle detecting means 50 isinputted to the microcomputer 36.

Next, operation of the present embodiment will be described hereinbelowby referring to FIG. 22. Laser beam emitted from the laser light source22 is reflected by means of the reflector 24 in a direction along thatof the beam scanner 26. In this case, if the horizontal azimuth of theshaft of the beam scanner 26 is preset at θ and the beam scanner 26 isrotated, scanning is effected by emitting laser beam on the line 8 to bedetermined through the projection window 43a. In this case, scanningwith the laser beam is effected within a perpendicular plane, and ahorizontal azimuth θ in the perpendicular plane, i.e., the horizontalazimuth θ of the beam scanner 26 is detected by the angle detectingmeans 50. Due to this scanning with laser beam, continuous luminousspots appear on the line 8 to be determined.

These continuous luminous spots are picked up by the television camera28, but it is to be noted that in case of such picking up of luminousspots, a solenoid valve controlling signal is outputted from the controlmeans 46 immediately before the picking up (before about 3 seconds),whereby the solenoid valve 42 is turned ON from OFF state. It results injetting of blast furnace exhaust gas into atmosphere in the furnacewhere scattering materials float through the nozzle 42c. In this case, apressure of the exhaust gas in the gas holder 42 is fixed at a 2-5 timeshigher value than the pressure in a furnace having usually a pressure of1.7 atm. Further a diameter of the nozzle 42c is 1-2 inches. Moreover ithas been found that dust purge effect in the diametrical direction of ablast furnace is remarkable with respect to such blast furnace having anaverage dust concentration of 20 g/N m³, a means gas velocity of 1.2m/sec., and an inner diameter of 7 m, respectively, in the case where anozzle with a diameter of 1-2 inches is employed, and a pressure of thegas holder is made to be about 3 times higher than the pressure in theblast furnace. Exhaust gas jetting is directed to the vicinity ofoptical path of laser beam so that a dust concentration in the vicinityof the optical path is permitted to decrease. As a result of jettingexhaust gas under the aforesaid condition, its average dustconcentration could be reduced to about 1/3.

As described above, exhaust gas is jetted into the atmosphere in afurnace, and then picking up of image signal is carried out for about 1second by utilizing the television camera 28. Then, control signal isoutputted from the control means 46 upon the solenoid valve 42 at thetime when the picking up by means of the television camera 28 wasfinished, whereby the solenoid valve 42 comes to be closed state, andthe exhaust gas jetting is stopped. A picture signal obtained by thetelevision camera 28 is signal-processed by means of the signalprocessing circuit 44, and then the signal thus processed is inputted tothe position coordinate detection circuit 34. In the position coordinatedetection circuit 34, two-dimensional position coordinates (H, V) on thetelevision picture of an image of line to be determined are detectedfrom the picture signal obtained. The two-dimensional positioncoordinates (H, V) obtained are inputted to the microcomputer 36. In themicrocomputer 36, three-dimensional position coordinates (X, Y, Z) withrespect to the respective points of the line 8 to be determined on thesurface 30 of charge in the furnace are operated by means of coordinateconversion from the two-dimensional position coordinates (H, V), thehorizontal azimuth θ of the beam scanner 26 inputted from the angledetecting means 50, and a geometrical configuration constant which haspreviously been set in the microcomputer 36 in respect of the beamscanner 26 and the television camera 28. As the result, thethree-dimensional position coordinates (X, Y, Z) obtained is indicatedin the indicator 48.

In this connection, each azimuth of the beam scanner 26 is varied with,for instance, every 5 degrees and a number of lines to be determinedbeing imagined on the surface 30 of charge in the furnace are determinedas mentioned above, and when an enveloping surface of the resultingthree-dimensional position coordinates is extracted, a shape of thesurface of charge in the furnace can be obtained. It is preferable thatthe nozzle 42 is swung so as to conform the horizontal azimuth of thebeam scanner 26 by the use of a driving means.

Next, another embodiment of the present invention will be illustrated inFIG. 23 in which the surface of charge in a furnace is divided intothree regions, A, B, and C to be determined, nozzles 54a, 54b and 54care disposed so as to correspond to the respective regions to bedetermined, and at the same time a nozzle 54 for cleaning awayscattering materials on a pickup passage is provided immediately below alight receiving window 43. As shown in FIG. 23, the present embodimentcomprises four solenoid valves 52, 52a, 52b and 52c connected to a gasholder 42a through a gas passage, respectively, and the nozzles 54, 54a,54b and 54c connected to the respective solenoid valves. The respectivesolenoid valves are switched by means of control signals supplied from acontrol means 46. The nozzles 54a, 54b and 54c are arranged so as todirect the regions A, B and C to be determined, respectively, whilst thenozzle 54 is arranged so as to direct to the pickup direction. Thepresent embodiment is practiced in such that first, the solenoid valves52 and 52a are made to open, thereby to jet exhaust gas from the nozzles54 and 54a, and image signal is picked up in the case where the region Ais determined. In the same manner, exhaust gas is jetted from thenozzles 54 and 54b in the case where the region B is determined, whilstexhaust gas is jetted from the nozzles 54 and 54c in the case where theregion C is determined, and then both the regions B and C are determinedthrough picking up of image signal, respectively. According to thepresent embodiment, since scattering materials in the pickup passage arecleared away, there is such an advantage in that a favorabledetermination can be effected even in a case where light scattering dueto dust in the passage is remarkable.

In this connection, according to the aforesaid embodiment, a ratio as tothe case where determination was possible immediately after 30 secondsor less from charging of a raw material into a furnace wasconventionally 60%, whilst such ratio was improved to a value of 90% inthe present embodiment.

In addition, in such a case where a line to be determined is picked upby the use of a television camera, it is practiced in such that a secondline to be determined is imaged in the vicinity of the (first) line tobe determined as in the first and second inventions mentioned above toextract two pictures, subtraction is effected between these pictures,and two-dimensional position coordinates are extracted on the basis ofthe pictures obtained, so that a passive spot image derived from afurnace core luminous part or the like can be removed. In such a case,the system as illustrated in FIG. 7 is utilized.

What is claimed is:
 1. A method for determining the shape of a surfaceto be determined in an atmosphere of scattering materialscomprising:irradiating light on a first line to be determined beingimagined on said surface to be determined in the atmosphere ofscattering materials to extract a first picture signal at the time ofpicking up said first line; irradiating light on a second line on saidsurface to be determined being imagined at a position a prescribeddistance apart from said first line to extract a second picture signalat the time of picking up said second line; substracting said secondpicture signal from said first picture signal to extract a fresh picturesignal; and applying said fresh picture signal to the two-dimensionalposition coordinates of a first image of said first line in the firstpicture signal to extract three-dimensional position coordinates of saidfirst line on said surface to be determined through coordinateconversion of said two-dimensional position coordinates.
 2. A method fordetermining the shape of a surface to be determined in an atmosphere ofscattering materials comprising:scanning with a laser beam along a firstline to be determined being imagined on said surface to be determined inthe atmosphere of scattering materials to extract a first picture signalthrough picking up of said first line by a television camera; scanningwith a laser beam along a second line to be determined being imagined ata position on said surface to be determined a prescribed distance apartfrom said first line to extract a second picture signal through pickingup of said second line by said television camera; subtracting a portionof said second picture signal corresponding to the intersection of aspecified scanning line and the image of said second line in said secondpicture signal from a portion of said first picture signal correspondingto the intersection of said scanning line and the image of said firstline in said first picture signal to extract a fresh video signal;extracting the two-dimensional position coordinates of said point ofintersection of the image of said first line with said scanning linefrom a signal corresponding to a laser locus image on said scanning linein said fresh video signal; repeating the previous two steps for eachscanning line in said first picture signal to extract thetwo-dimensional position coordinates of the respective points of theimage of said first line; and extracting three-dimensional positioncoordinates of said first line on said surface to be determined bysubjecting said two-dimensional position coordinates of the respectivepoints of the image of said first line to coordinate conversion.
 3. Themethod for determining the shape of a surface to be determined in anatmosphere of scattering materials of claim 2, furthercomprising:jetting gas of a higher pressure than that of said atmosphereof scattering materials thereinto prior to extracting said first picturesignal and said second picture signal.
 4. A system for determining theshape of a surface to be determined in an atmosphere of scatteringmaterials comprising:projector means for projecting light upon a firstline to be determined being imagined on the surface to be determined inthe atmosphere of scattering materials and upon a second line on saidsurface to be determined a prescribed distance apart from said firstline; gas jetting means for jetting gas of a higher pressure than thepressure of said atmosphere of scattering materials thereinto; pickupmeans for picking up said first and second lines after jetting said gasby means of said gas jetting means, thereby to output a picture signal;position coordinate detecting means for extracting two-dimensionalposition coordinates of said first line on a picture from said picturesignal by comparing the signal corresponding to said first line with asignal representative of the difference between the picture signalscorresponding to said first and said second lines; and arithmetic unitmeans for generating three-dimensional position coordinates of saidfirst line on said surface to be determined by subjecting saidtwo-dimensional position coordinates to coordinate conversion.
 5. Thesystem for determining the shape of a surface to be determined in anatmosphere of scattering materials of claim 4 wherein said gas jettingmeans comprises:a gas holder for storing dust-free gas; a solenoid valveconnected to said gas holder and operating to open and close a gaspassage; and a nozzle connected to said solenoid valve and operating tojet said dust-free gas into said atmosphere of scattering materials. 6.The system for determining the shape of a surface to be determined in anatmosphere of scattering materials of claim 4, wherein said gas jettingmeans comprises a plurality of gas jetting means corresponding todetermination regions defined by plurally dividing said surface to bedetermined, and another gas jetting means disposed in the vicinity ofsaid pickup means for clearing away said scattering materials on thepickup passage.
 7. A system for determining the shape of a surface to bedetermined in an atmosphere of scattering materials comprising:laserbeam scanning means for scanning a first line being imagined on saidsurface to be determined in the atmosphere of scattering materials and asecond line on said surface to be determined being imagined at aposition a prescribed distance apart from said first line by said laserbeam scanning means at a prescribed scanning rate; pickup means forpicking up said first line and said second line to poutput a firstpicture signal representative of said first line and a second picturesignal representative of said second line; signal processing means forremoving high frequencies from said signals, distinguishing between saidsignals, and adjusting the relative amplitudes of said signals; picturesignal substracting means for subtracting said second picture signalfrom said first picture signal to extract a fresh picture signal aftersaid first and second signals have been processed by said signalprocessing means; position coordinate detecting means for extractingtwo-dimensional position coordinates of an image of said first line onthe picture on the basis of said fresh picture signal;and an arithmeticunit means for subjecting said two-dimensional position coordinates tocoordinate conversion by utilizing geometrical constants including themounting position coordinates of said laser beam scanning means and saidpickup means to extract three-dimensional position coordinates of saidfirst line to be determined, thereby to obtain the shape of said surfaceto be determined.
 8. The system for determining the shape of a surfaceto be determined in an atmosphere of scattering materials of claim 7,further comprising:gas jetting means for jetting gas of a higherpressure than that of said atmosphere of scattering materials thereintoprior to effecting scanning with said laser beam scanning means.